logic

"Logic" is a fascinating word with a few closely related but distinct meanings. It can refer to a formal field of study, a way of thinking, or the sense of reason behind a decision. Here are the most common ways you'll encounter it.

1nounclear, sound reasoning

When you think through a problem carefully, step by step, and reach a conclusion that makes sense — that is logic. It is the ability to connect ideas in a way that is rational and consistent. If your argument has good logic, people will find it hard to disagree with.

everyday language · Modern, widely used

Her logic was so clear that everyone in the room agreed with her conclusion.

I don't follow your logic — how does spending more money save us money?

He solved the puzzle using simple logic, without any guessing.

2nounthe reason or sense behind something

Sometimes 'logic' refers to the reason why something works the way it does, or why someone made a particular choice. You might say 'I understand the logic' to mean 'I see why that makes sense.'

everyday language · Modern, widely used

The logic behind the new policy is to reduce costs.

I can see the logic of leaving early to avoid traffic.

There is a certain logic to keeping your workspace tidy — you waste less time searching for things.

3nounthe academic study of reasoning

Logic is also a formal subject studied in philosophy and mathematics. In this sense, it is the science of how to build valid arguments and avoid errors in thinking. It uses rules and symbols to test whether conclusions truly follow from their starting points.

philosophy / academia · Modern, widely used

She took a course in logic as part of her philosophy degree.

In formal logic, a statement is either true or false — there is no middle ground.

Mathematical logic is the foundation of computer science and programming.

4nounthe rules that control how a system works

In technology and computing, 'logic' refers to the set of rules that tell a machine or program what to do. Think of it as the brain of a system — the instructions that decide what happens next.

technology / computing · Modern, widely used

The developer wrote the business logic for the payment system.

A small error in the logic of the program caused it to crash.

The logic of the circuit determines how the device responds to input.